Digital cellular communications systems, paging systems, land mobile radio, and mobile battlefield communication systems are called upon to operate effectively in increasingly adverse spectral environments. Obstacles to digital mobile communications include non-stationary co-site interference, ambient communication signals, and hostile jamming interference. Typical interference levels can be very high, especially in a tactical environment, and can often exceed the desired signal by 60 decibels or more. Such levels overwhelm the operational capabilities of current tactical and commercial radio systems. Furthermore, PCS, paging, and cellular communication networks that incorporate spread-spectrum technologies, such as CDMA, increasingly face capacity limitation caused in part by growing spectral clutter. The presence of ambient high power partialband and narrowband signals often precludes frequency reuse by spread-spectrum communication systems.
Therefore, there is a need for a method and apparatus for reducing the impact of undesirable spectral components in a communications system.